Maskable PWA icon has some issues

[castanearie]

Noticed that on my Android the home screen icon looked a bit cropped, so decided to investigate, and found the following issues with the maskable icon:

• the image file maskable-512x512.png is actually 1024x1024px
• the icon should be scaled to fit within the minimum safe area (can be checked with https://maskable.app/)
• the icon should be placed on a background the extends all the way to the edge, instead of the pre-rounded edges and blue infill
• I believe in the manifest the purpose should be maskable alone, instead of any maskable